1. Technical Field
This invention relates to apparatus for transferring ink from one roll to another roll in a printing press. More particularly, this invention relates to a ductor assembly for transferring ink between a fountain roll and an ink receiving roll which are rotating at different surface speeds.
2. Prior Art
A known printing press has a fountain roll (ink supply roll), and an ink receiving roll. A moving ductor roll contacts the fountain roll, and ink is transferred from the fountain roll to the ductor roll. The ductor roll then moves to the ink receiving roll. The ductor roll contacts the ink receiving roll, and ink is transferred from the ductor roll to the ink receiving roll. The ink receiving roll transfers the ink through an ink train to a roll which applies the ink to the material being printed.
Typically the fountain roll rotates relatively slowly, and the ink receiving roll rotates much more rapidly. The ductor roll is rotating relatively slowly when it contacts the rapidly rotating ink receiving roll. The mismatch in speeds between the ductor roll and the ink receiving roll causes a shock which travels through the ink train. This shock can cause printing errors. The mismatch in speeds also adversely affects ink transfer and ink control.